Programmable logic devices (PLDs) exist as a well-known type of integrated circuit (IC) that may be programmed by a user to perform specified logic functions. There are different types of programmable logic devices, such as programmable logic arrays (PLAs) and complex programmable logic devices (CPLDs). One type of programmable logic device, known as a field programmable gate array (FPGA), is very popular because of a superior combination of capacity, flexibility, time-to-market, and cost.
An FPGA typically includes an array of configurable logic blocks (CLBs) surrounded by a ring of programmable input/output blocks (IOBs). The CLBs and IOBs are interconnected by a programmable interconnect structure. The CLBs, IOBs, and interconnect structure are typically programmed by loading a stream of configuration data (known as a bitstream) into internal configuration memory cells that define how the CLBs, IOBs, and interconnect structure are configured. Additionally, an FPGA may include embedded memory, such as block random access memories (BRAMs), one or more microprocessors, sometimes referred to as embedded cores, multipliers, transceivers, and digital clock managers (DCMs). The combination of components on an FPGA may be used for system-level integration, sometimes referred to as “system-on-a-chip” (SOC). Examples of FPGAs include the Virtex-II, Virtex-4, and Spartan families of FPGAs available from Xilinx, Inc.
Historically, FGPAs have not been employed in network processing applications. Rather, network devices, such as routers, employ dedicated, special purpose components for processing packets that propagate through the network. Conventionally, network devices employ network processors or application specific integrated circuits (ASICs) to provide the desirable packet processing/network processing functions. Such processor- or ASIC-based architectures, however, are static in nature, providing a fixed amount of resources for packet processing/network processing functions. Accordingly, there exists a need in the art for more flexible message processing architectures.